Biological Activities of Extracts of Different Spices and Plants

Aqueous, alcoholic and hexanic extracts of different spices and plants materials were investigated for their antioxidant and antibacterial activities. The total flavonoid contents of extracts varied from 1.65 μg quercetin equivalent/mg (water extract of red pepper) to 340.13 μg quercetin equivalent/mg (alcoholic extract of miswak). The aqueous extract of black tea and the ethanolic extracts of both cinnamon and clove displayed the highest total phenolic contents with 196.57, 194.06 and 198.16 μg gallic acid equivalent/mg, respectively. Antioxydant activities of extracts were assessed using DPPH-free radical scavenging method. Ethanolic and aqueous extracts of cinnamon, ethanolic extract of clove and aqueous extract of coffee displayed the strongest antioxidant activity with IC50 values of 1.45, 1.96, 2.16, 3.02 and 5.4 μg/ml, respectively. Antibacterial activities of extracts against several bacterial genera, known to be pathogenic to humans, were investigated using the agar well diffusion method. The hexanic extracts were effective against most of the microorganisms tested. Particularly, S. xylosus was found to be highly sensitive to most of the hexanic extracts and especially to those of miswak, clove and turmeric with minimal inhibitory concentrations values of 15.62 and 31.25 and 62.5 μg/mL, respectively.